392 Agassiz on the Relations between Animals 
restrial and arboreal types? Are not the aquatic Shrews inferior 
to the arboreal Insectivora? All these secondary questions will 
receive, in future, due attention and will no doubt he satisfacto- 
rily settled. But ‘there are families in which we can already see 
our way and arrive at precise conclusions. Among Carnivorous 
Mammalia we have three very distinct types, the Pinnipoda or 
Seals; the Plantigrada or Bears, and the Digitigrada, Dogs and 
Cats. Now even if objections were raised against the association 
of the Walrus with the common Seals, there can be no doubt of 
the inferiority of the latter when contrasted with Plantigrada and 
Digitigrada. ‘Their short fin-like legs, their clumsy body in con- 
nection with their aquatic marine life, assign them a lower position, 
and the Plantigrada must be cons sidered as intermediate between 
them and the Digitigrada. Now among Digitigrades, even if we 
take isolated genera, we are led to assign to the species with 
aquatic habits, an inferior position among their nearest relatives. 
‘The polar Bear comes decidedly nearer the Seals in all its habit id 
than any other species of that genus, and on sane hair sage 
bé considered as inferior to the terrestrial speci Again 
others, with their palmate fingers, rank lower em their — 
relatives: and we may even find that such considerations will 
hold good among the varieties of one and the same species ; or 
we have varieties among the Digitigrade Dogs in which the fin- 
gers are palmate, a character which is derived from the imperfect 
development of their legs, preserving throughout life their em- 
onic form; and these varieties among Dogs are the most play- 
ful and at the same time, most aquatic in their habits, preserving 
in their adult state eharacters of ‘the young and. habits of the 
lower types,—this playful tigpootiog andy universal even among 
the most ferocious of the Cat tribes J shall abstain purposely 
from tracing these compari§gns = highe? up ameng Monkeys, and 
in the human families, from ‘fear of alluding to exciting topics; 
but leave it to the philosophic observer to consider how far t 
idea of an aquatic Monkey is compatible with the high position 
which these animals hold in ¢he class of Mammalia; and how 
curious it is that in the human family there are races which differ 
so much in their natural dispositions, mode of life, habits and 
adaptation to higher civilization; and how closely these natural 
dispositions are connected with apparently th et peculiar- 
ities of structure 
pon reviewing the facts mentioned above, and the inferences 
derived from the facts, no impartial observer can in future deny 
the importance of the study of the natural relations between ani- 
mals and the media in which they live ; and the close connection 
which exists between them and the gradation of their structure. 
But this being the case, it must be a matter a po Re a the 
views so long entertained of the importance of this connection, 
a} 
SS ee 
